LOW COMMON MODE RESONANCE MULTIBAND RADIATING ARRAY

• US 20160285169A1
• Filed: 05/28/2015
• Published: 09/29/2016
• Est. Priority Date: 01/15/2015
• Status: Active Grant

• Current Assignee: CommScope Technologies, LLC (CommScope Holding Company, Inc.)
• Original Assignee: CommScope Technologies, LLC (CommScope Holding Company, Inc.)
• Inventors: Shooshtari, Alireza, Zimmerman, Martin L., Bisiules, Peter J.
• Granted Patent: US 9,698,486 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H01Q 1/246 specially adapted for base stations
• CPC Class Codes: H01Q 1/38 formed by a conductive layer on an insulating support patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142
• CPC Class Codes: H01Q 1/50 Structural association of antennas with earthing switches, lead-in devices or lightning protectors
• CPC Class Codes: H01Q 1/521 reducing the coupling between adjacent antennas
• CPC Class Codes: H01Q 21/062 using dipole aerials; H01Q21/067, H01Q21/068 take precedence
• CPC Class Codes: H01Q 21/26 Turnstile or like antennas comprising arrangements of three or more elongated elements disposed radially and symmetrically in a horizontal plane about a common centre
• CPC Class Codes: H01Q 9/285 Planar dipole H01Q9/065 takes precedence; patch antenna H01Q9/0407

Abstract

A higher band radiating element for use in a multiband antenna includes first and second dipole arms supported by a feedboard. The feedboard includes first and second matching circuits, each comprising a capacitor-inductor-capacitor (CLC) matching circuit. The matching circuit further includes a CM tuning circuit connecting a portion of the matching circuit to ground via a microstrip trace selected to pass lower band currents while blocking higher band currents. The CM tuning circuit moves the common mode resonance of the higher band support PCB down below the operating frequency of additional, lower band radiating elements present in the multiband antenna, which is preferable to moving the common mode resonance above the lower band frequencies.

Claims

1. A higher band radiating element for a multiband antenna having at least higher band elements and lower band elements, comprising:

a. first and second dipole arms, each dipole arm having a capacitive coupling area; and

b. a feedboard having a balun and first and second matching circuits coupled to the balun, the first matching circuit being coupled to the first dipole arm and the second matching circuit being coupled to the second dipole arm, the first and second matching circuits each comprising in series;

1. a stalk, coupled to the balun,

2. a first capacitive element;

3. an inductor; and

4. a second capacitive element, the second capacitive element being coupled to a dipole arm;

each matching circuit further comprising a common mode tuning circuit connecting the first capacitive element and the inductor to the stalk to move the common mode resonance of the matching circuits to a frequency below the lower band frequency.

2. The higher band radiating element of claim 1, wherein the common mode tuning circuit further comprises a microstrip line providing a DC connection to the stalk and having a length selected such that it appears as a high impedance at an operating frequency of the higher band radiating element.

3. The higher band radiating element of claim 2, wherein the common mode tuning circuit has a length selected such that it appears as a relatively low impedance at the operating frequency of the lower band radiating element.

4. The higher band radiating element of claim 1, wherein the first capacitive element and an area of the stalk comprise parallel plates of a capacitor and the feedboard substrate comprises a dielectric of a capacitor.

5. The higher band radiating element of claim 1, wherein the second capacitive element and dipole arm capacitive coupling area combine to form a capacitor that blocks out of band currents.

6. The higher band radiating element of claim 1, wherein the radiating element further comprises a cross dipole radiating element.

7. The higher band radiating element of claim 1, wherein the higher band radiating element further comprises a high band radiating element of a dual-band array.

8. The higher band radiating element of claim 1, wherein the higher band radiating element has a first operational frequency band within a range of about 1710 MHz-2700 MHz, and each lower band radiating element has a second operational frequency band within a range of about 698 MHz-960 MHz.

9. The radiating element of claim 8, wherein the common mode tuning circuit has a length selected to pass low band current and block high band current.

10. The higher band radiating element of claim 1, wherein the common mode tuning circuit has a length such that it does not de-tune the higher band radiating element.

12. The multiband antenna of claim 10, wherein the first operational frequency band comprises a mobile communications low band and the second operational frequency band comprises a mobile communications high band.

13. The multiband antenna of claim 10, wherein the first operational frequency band is located within an approximate range of 698 MHz to 960 MHz, and the second operational frequency band is located within an approximate range of 1710 MHz to 2170 MHz.

11. A multiband antenna, comprising:

a. a first array of first radiating elements having a first operational frequency band; and

b. a second array of second radiating elements having a second operational frequency band, the second operational frequency band being higher than the first operational frequency band, the second radiating elements further comprising;

a. first and second dipole arms, each dipole arm having a capacitive coupling area; and

b. a feedboard having a balun and first and second matching circuits coupled to the balun, the first matching circuit being coupled to the first dipole arm and the second matching circuit being coupled to the second dipole arm, the first and second matching circuits each comprising in series;

1. a stalk, coupled to the balun,

2. a first capacitive element;

3. an inductor; and

4. a second capacitive element, the second capacitive element being associated with one of the first and second dipole arms,

each matching circuit further comprising a common mode tuning circuit connecting the first capacitive element and the inductor to the stalk, the common mode tuning circuit comprising a microstrip line dimensioned to short any induced low band currents to the stalk without substantially affecting high band currents, thereby moving common mode resonance down below the second operational frequency band.